The conventional sewing process will be describe by way of the sewing of a zipper on a skirt. FIGS. 1(A)-(C) show three different types of flaps (each of which is the portion of the skirt covering the zipper) of a workpiece. FIGS. 2(A) and (B) are exploded perspective and right-hand side elevational views, respectively, of a workpiece without a lining sewn thereon and FIGS. 3(A) and (B) are exploded prespective and right-hand side elevational views, respectively, of a workpiece with a lining sewn thereon which show relationship between parts of the workpieces, respectively.
In these FIGS., 1 is the surface cloth, 2 is the lining, 3 is the zipper having the slider 3a and fastener tapes 3b, 3b and 4 is the flap of the workpiece 1. There are three different types of flaps as shown in FIGS. 1(A)-(C).
As shown in FIGS. 2(A) and 3(A), the zipper 3 is sewn by the sewing width L on the surface cloth 1a which is unlined or lined. FIGS. 4(A)-(F) show the conventional sewing process when the flap is a left flap. FIG. 4(A) shows the initial sewing step in which the slider 3a is retracted to substantially the central area of the length of the zipper 3. As shown in FIG. 4(A), the operator starts to sew the zipper 3 on the workpiece at the leading left-hand side corner thereof with his both hands placed on the surface cloth 1 on the opposite sides of the zipper 3. After the flap has been sewn at its inner side edge on the zipper 3 halfway in the longitudinal direction of the zipper 3, the sewing machine 10 is once stopped and the slider 3a is pulled to the leading end of the zipper (FIG. 4(B)). This is to prevent the needle 11 from inadvertently interfering with the slider 3a. The sewing operation then continues to a predetermined position in the longitudinal direction of the zipper and the workpiece is rotated by 90.degree. in the arrow direction with the needle held in its lowered position (FIG. 4(C)). The sewing operation progresses along the trailing end of the zipper 3 by the sewing width L and the workpiece is again rotated by 90.degree. in the arrow direction with the needle held in its lowered position (FIG. 4(D)). After the lower side of the free end portion of the flap 4 has been sewn on the zipper halfway in the longitudinal direction of the zipper while turning the flap over, the sewing machine 10 is stopped and the slider 3a of the zipper 3 is moved back to substantially the central area of the length of the zipper 3 (FIG. 4(E)). Thereafter, the sewing operation is resumed to continue to sew the flap to a predetermined position in the longitudinal direction of the zipper whereupon thread cutting is effected to complete the sewing operation (FIG. 4(F)).
Since the sewing process is basically conducted manually by the operator, the process has the following drawbacks:
(I) The surface cloth and zipper (or lining) tend to displace relative to each other.
(II) The manipulation of the slider is troublesome.
(III) The formed seam or seams tend to be meandering.
(IV) The sewing width is not uniform.
(V) Safety in the sewing operation is not assured.
(VI) A highly skilled hand is required to obtain a final sewn product of high quality.
The present invention has been developed to eliminate the drawbacks inherent in the above-mentioned prior art and a first object of the present invention is to provide an automatic sewing machine exclusively used for sewing a zipper on a workpiece automatically and precisely.
Another object of the present invention is to provide a process for sewing a zipper on a workpiece safely and effectively by the use of an automatic sewing machine designed to exclusively carry out the process.
A further object of the present invention is to provide a cassette type zipper setting device adapted to be detachably attached to an automatic sewing machine exclusively used for sewing a zipper on a workpiece for temporally setting the zipper and the workpiece.
A further object of the present invention is to provide a flap turning-over device adapted to automatically turn the flap over when the lower side of the flap is sewn by the sewing machine.
A further object of the present invention is to provide the configuration of an intermediate holding-down member to cooperate with the above-mentioned flap turning-over device for acceleration of the flap turning-over as the lower side of the flap is sewn and for effectively holding a workpiece as the needle is pulled out of the workpiece.